Image reading apparatus and operation device

ABSTRACT

A plurality of touch switches includes a first switch and a second switch provided adjacent to each other. A distance between an electrode and a surface of a cover at the location of the first switch is smaller than a distance between an electrode and the surface of the cover at the location of the second switch.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to imaging and, moreparticularly, to an apparatus including an image reading unit, such as ascanner, a printer, a facsimile machine, a copying machine, and amultifunction peripheral (MFP).

2. Description of the Related Art

Japanese Patent Application Laid-Open No. 2009-88759 discusses an MFPwhich includes an image reading unit. The device includes a readingunit, which is configured to read an image of a document set on areading surface, and a pressing plate, which can open on the readingsurface. On an upper surface of the pressing plate, an operation unit,which includes a plurality of input keys, and a display device, such asa liquid crystal display (LCD) panel, are provided.

U.S. Patent Application Publication No. 2009/0033636 Al discusses acapacitive touch panel input device. The capacitive touch panel inputdevice includes a substrate and a spacer. A plurality of sensorelectrodes is implemented on the capacitive touch panel input device.The spacer is set on each sensor electrode.

The spacer includes a first block provided on the electrode and a secondblock provided within the first block. The conductivity of the secondblock is lower than that of the first block. Accordingly, theabove-described conventional method prevents an error input by hardlyreceiving the affect from adjacent sensor electrodes.

Another conventional method discussed in the Japanese Patent ApplicationLaid-Open No. 2009-88759 includes an operation unit that has a structureof a mechanical-contact key, such as a tactile switch. However, in termsof lower costs and appropriate component arrangement and design, theoperation unit can be replaced with the capacitive input device, such asthe one discussed in U.S. Patent Application Publication No.2009/0033636 A1.

In the apparatus discussed in the U.S. Patent Application PublicationNo. 2009/0033636 A1, it is required to divide the spacer into a multipleof minute blocks and to arrange them at precise locations. Accordingly,the configuration of a switch may become too complicated to easilymanufacture the stitch. Furthermore, it may become difficult to reducethe costs of manufacture thereof.

The above-described conventional method intends to reduce error inputsby using the second block. However, if the plurality of electrodes isarranged at a high density, if the user (operator) has touched a touchpanel at a location between mutually adjacent electrodes, it isimpossible to predict which of the mutually adjacent electrodes sensesthe operation.

If the switch not desired by the operator turns on, the input becomes anerror. As a result, a malfunction of the apparatus may occur.

SUMMARY OF THE INVENTION

The present invention is directed to a method that utilizes a differencein the frequency of use of switches included in an operation unit of animage reading apparatus, which is touched by the operator. Morespecifically, the present invention is directed to a method forimplementing switches whose two adjacent switches having a simplestructure and having mutually different sensitivity to preferentiallyinput an input via one switch than the other of mutually adjacentcapacitance touch switches when the operator has touched the touchingsurface at a location between the two switches.

According to an aspect of the present invention, an apparatus includes areading unit configured to read an image of a document set on a readingsurface, a pressing plate capable of opening relative to the readingsurface, and an operation panel provided on an upper surface of thepressing plate. The operation panel includes a cover, and a plurality oftouch switches provided at different locations of the cover, each touchswitch including an electrode configured to detect a capacitance. Theplurality of touch switches includes a first switch and a second switchprovided adjacent to each other. In the apparatus, a dent is formed on asurface of the cover at a location of the first switch. A distancebetween the electrode and the surface of the cover at the location ofthe first switch is smaller than a distance between the electrode andthe surface of the cover at the location of the second switch.

Further features and aspects of the present invention will becomeapparent from the following detailed description of exemplaryembodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate exemplary embodiments, features,and aspects of the invention and, together with the description, serveto explain the principles of the present invention.

FIGS. 1A and 1B are perspective views illustrating an exemplaryconfiguration of an apparatuses according to an exemplary embodiment ofthe present invention.

FIGS. 2A and 2B illustrate a state of display on an operation panel ineach of power-off and power-on states.

FIGS. 3A and 3B illustrate an exemplary structure of a panel unit.

FIGS. 4A and 4B are cross sections of a capacitance touch switch.

FIGS. 5A through 5C illustrate a state of keys displayed in each of aplurality of modes.

DESCRIPTION OF THE EMBODIMENTS

Various exemplary embodiments, features, and aspects of the inventionwill be described in detail below with reference to the drawings.

In the present specification, apparatuses which have an image readingunit configured to read an image of a document, such as a scanner, aprinter, a facsimile apparatus, a copying machine, or an MFP, will becollectively referred to as an “image reading apparatus”.

FIGS. 1A and 1B illustrate an exemplary configuration of an imagereading apparatus according to an exemplary embodiment of the presentinvention. FIG. 1A illustrates a state of the image reading apparatus inwhich a pressing plate thereof is closed while in FIG. 1B, the pressingplate is opened.

The image reading apparatus, within a housing thereof, includes areading unit having a flatbed scanner, a recording unit, and a controlunit 5. The reading unit reads an image of a document set on a readingsurface. The recording unit prints a document image read by reading thedocument on a sheet. The control unit 5 controls an operation of theentire image reading apparatus. The reading unit and the recording unitare implemented by a well-known art, such as the conventional devicediscussed in the Japanese Patent Application Laid-Open No. 2009-88759.Accordingly, the reading unit and the recording unit will not bedescribed in detail in the present specification.

The control unit 5 is constituted by a controller board, which includesa central processing unit (CPU), a memory, and various input/output(I/O) interfaces. A pressing plate 6 is provided at the top portion ofthe image reading apparatus and can open on a reading surface 2.

After appropriately installing the image reading apparatus to a user(operator)'s environment, the operator can access the image readingapparatus from the left (the front side) of FIGS. 1A and 1B.

Referring to FIG. 1A, the pressing plate 6 is a document positioningplate cover, which presses the document when closed. A panel unit 1 isprovided on the upper surface of the pressing plate 6.

The panel unit 1 includes a panel cover 11. On the panel cover 11, adisplay unit 4 and various operation keys (input switches) are installedclosely to one another. In addition, a power button 111 is installed tothe panel cover 11. The operation keys are capacitance touch switchesexcept the power button 111.

The capacitance touch switch is a touch switch that detects thecapacitance, which varies when the operator touches its touch-operationsurface with his/her finger, and recognizes the detected capacitance asan input. The detailed configuration of and an operation executed by thecapacitance touch switch will be described in detail below.

The display unit 4 includes a display window 4 a, which is constitutedby a transparent member. When the display unit 4 is retracted, thedisplay unit 4 is tilted just onto the surface of the panel cover 11, asillustrated in FIG. 1A. The display unit 4 can be pivoted by theoperator to be tilted up to become oriented towards the front of theimage reading apparatus. In other words, when the display unit 4 isretracted (pivoted down), a display of the display window 4 a can beviewed from above. On the other hand, when the display unit 4 isextended (pivoted up), the display of the display window 4 a can beviewed from the front.

The power button 111 has a structure of a mechanical contact key, suchas a tactile switch. If the operator presses the power button 111 whenthe image reading apparatus has been powered off, the apparatus ispowered on. On the other hand, if the operator presses the power button111 when the image reading apparatus has been powered on, the apparatusis powered off.

Referring to FIG. 1B, the pressing plate 6 is pivotably mounted to aframe 9 in a back portion (the opposite portion of the front portionthereof) at two locations by using hinges 8. The reading surface 2 isconstituted by a transparent glass plate. The operator sets a documenton the upper surface of the reading surface 2 in a face-down state(i.e., with the surface of the document to be read facing downwards).The perimeter of the glass plate is covered with a cover to be mountedto the frame 9.

A press-contact sheet 7 is mounted to the inner (back) surface of thepressing plate 6 in order to prevent floating of the document set on thereading surface 2 by applying pressure onto the document. Vertical playis provided to engagement between the hinge 8 and the pressing plate 6.Accordingly, the image reading apparatus can read an image of a thickbook document.

The control unit 5 controls various operations executed by the imagereading apparatus. More specifically, the control unit 5 controls anoperation of each of the reading unit and the recording unit. Inaddition, the control unit 5 controls the display by the display unit 4,a switch input that is input by an operation on the touch switch, andthe display of the touch switch.

As will be described below, the control unit 5 controls a plurality ofoperation modes of the image reading apparatus. More specifically, thecontrol unit 5 toggles on and off a backlight of the touch switch (i.e.,light for illuminating the touch switch from behind) according to eachselected operation mode.

FIGS. 2A and 2B are top views of the image reading apparatus, whichillustrate a status of display on an operation panel (operation device)provided to the panel cover 11 on the upper surface of the pressingplate 6.

In the example illustrated in FIG. 2A, the image reading apparatus hasbeen powered off. Various operation keys of an operation unit of theimage reading apparatus are out of view of the operator except the powerbutton 111 and a jog wheel 101 d.

In the example illustrated in FIG. 2B, the image reading apparatus hasbeen powered on and all the operation keys are displayed in a lit state.When the key is displayed in a lit state, the operator can validly inputinformation via the operation key displayed in the lit state.

In the example illustrated in FIG. 2B, the operation key includes a homekey 101 b, a return key 101 c, which can be operated to a previousstate, a monochromatic copy key 101 h, a color copy key 101 i, and astop key 101 j. The monochromatic copy key 101 h is a key forinstructing the start of a monochromatic copy operation or amonochromatic image scan operation. The color copy key 101 i is a keyfor instructing the start of a color copy operation or a color imagescan operation. The stop key 101 j is a key for instructing thediscontinuation of the current copy operation or scan operation.

In addition, the operation key includes a function key 101 a. Thefunction key 101 a is constituted by three keys, which can be operatedfor selecting a display item displayed on a screen of the display unit4. Furthermore, the operation key includes four-arrow (four-direction)key 101 f and a jog wheel 101 d. The four-direction key 101 f can beoperated to move a cursor up, down, left, or right on the screendisplayed on the display unit 4. The jog wheel 101 d has a wheel-likeshape and can be operated to move the cursor.

The operation key includes an OK key 101 e and plus-minus (“+” and “−”)keys 101 g. The OK key 101 e can be operated to finally inputting anoperator selection. The plus-minus keys 101 g can be operated to setnumerical values, such as the number of copies.

Each of the above-described operation keys is a capacitance touchswitch, which includes a backlight. The backlight of each operation keycan be independently turned on or off. When the backlight is turned on,a graphic (mark), which is uniquely assigned to the corresponding key,is displayed. Accordingly, the operator can easily recognize theoperation key. On the other hand, when the backlight of the operationkey is turned off, the mark on the key become hardly recognizable forthe operator. Note that the meaning of “turned off” contains not onlythe backlight becoming off completely, but also becoming alight with aweak power.

FIGS. 3A and 3B illustrate an exemplary configuration of the panel unit1. More specifically, FIG. 3A is an exploded perspective view of alaminated structure of the panel unit 1. FIG. 3B is a top view of thepanel unit 1.

Referring to FIG. 3A, the panel unit 1 includes a five-layer laminatedstructure including, in order from the front (upper) surface to the back(bottom) surface, the panel cover 11, an elastic sheet 12, a light guideelement group 13, an elastic sheet 14, and a circuit substrate 15. Thepanel unit 1, as a whole, is an integrated structural member, which isclosely laminated together by using the elastic sheet 12 and the elasticsheet 14.

More specifically, the elastic sheet 12 (a first elastic sheet), whichis a translucent sheet, is laminated between the panel cover 11 and thelight guide element group 13 to closely attach the panel cover 11 andthe light guide element group 13 together.

Similarly, the elastic sheet 14 (a second elastic sheet), which has asheet-like shape, is inserted between the light guide element group 13and the circuit substrate 15 to closely attach the light guide elementgroup 13 and the circuit substrate 15 together. It is not necessary thatthe elastic sheet 14 is translucent. Both the elastic sheets 12 and 14are made of a nonconductive insulating material.

The panel cover 11 is an integrated seamless board-like transmissive(transparent or translucent) member. The panel cover 11 is made of aplastic material, such as acryl, acrylonitrile butadiene styrene (ABS),polycarbonate (PC), methyl methacrylate-butadiene-styrene resin (MBS),or styrenic-block-copolymers (SBC), or a glass material.

Each of the elastic sheets 12 and 14 is one integrated (non-divided)sheet, which is commonly provided for a plurality of electrodes. Becauseeach of the elastic sheets 12 and 14 is an integrated (non-divided)sheet, it becomes easy to assemble the operation panel.

In assembling the operation panel, the panel cover 11 and the lightguide element group 13 should be completely closely attached together bylaminating the elastic sheet 12 between them without any gap or space.This is because if the panel cover 11 and the light guide element group13 are not completely closely attached together and if an air gap of lowconductivity may arise due to the loose attachment between them,variation of the capacitance may not be stably detected. As a result,the reliability of the capacitance touch switch may degrade.

Furthermore, in order to easily exchange the panel cover 11 in amaintenance operation, the elastic sheet 12 should be easily removable,even after they are once closely laminated, without any residual bond.In order to achieve the sufficiently close attachment properties and thehighly easy removability of the elastic sheet 12 at the same time, thepresent exemplary embodiment uses a self-tack elastic sheet for theelastic sheet 12, which can be adhered without using a bond. For theelastic sheet described above, a gel sheet can be used.

The elastic sheet 14, which is used for closely attaching the lightguide element group 13 and the circuit substrate 15 (on the surfaces ofthe plurality of electrodes) together, has the same characteristic asthat of the elastic sheet 12. Accordingly, for the elastic sheet 14, theself-tacking elastic sheet, such as a gel sheet, can be used.

It is not always necessary that both the elastic sheets 12 and 14 aregel sheets. In other words, either one of the elastic sheets 12 and 14only can be a gel sheet. In addition, a sheet which is different from agel sheet and made of a material having the same self-tacking propertiesand elasticity can be used as the elastic sheets 12 and 14. Furthermore,a two-sided adhesive tape that cannot be easily damaged when removed,such as a two-sided adhesive tape made by using polyethyleneterephthalate (PTE), can be used.

FIG. 3B illustrates an exemplary arrangement of light guide elements,which are included in the light guide element group 13 and arranged onthe circuit substrate 15. Referring to FIG. 3B, the light guide elementgroup 13 includes light guide elements 103 a through 103 j, which arearranged at locations corresponding to touching locations of thecapacitance touch switch.

FIGS. 4A and 4B are cross sections of a capacitance touch switch. FIG.4A is an A-A cross section of the plus-minus (“+” and “−”) keys 101 gillustrated in FIG. 2B.

On the surface of the panel cover 11 on its back side, a light-shieldinglayer 101 k is formed by printing that uses a black ink. On thelight-shielding layer 101 k, a transmissive graphic portion 101 m, whichincludes a light-transmissive portion that is partially not subjected toprinting using the black ink, is formed.

Viewed from above, the transparent graphic portion 101 m takes aspecific graphical shape. In the example illustrated in FIGS. 4A and 4B,the transparent graphic portion 101 m takes a shape of a graphicconstituted by the symbols “+” and “−” surrounded by a rectangle asillustrated in FIG. 2B.

The panel cover 11 is translucent. Accordingly, if the transparentgraphic portion 101 m is illuminated with light by the backlight frombehind (from the bottom), the graphical shape of the transparent graphicportion 101 m can be recognized by the operator. If the backlight isturned off, the graphical shape of the transparent graphic portion 101 mis not illuminated with light (i.e., turns completely dark to becomeless recognizable). Therefore, in this state, the operator cannotrecognize the graphical shape of the transparent graphic portion 101 m.

As a result of an experiment conducted by the inventors, by using thepanel cover 11 made of a translucent gray/smoke material, it became verydifficult for the operator to visually recognize the transparent graphicportion 101 m when the backlight had been turned off. In this state, thegraphical shape of the transparent graphic portion 101 m was actuallyvisually unrecognizable for the operator. Accordingly, the contrastbetween the graphical display on-state and the graphical displayoff-state became more intense.

The panel cover 11 is constituted by one integrated board-like member.Accordingly, if the backlight is turned off, the switches except thepower button 111, the jog wheel 101 d, and the OK key 101 e become lessrecognizable. Accordingly, in this state, the operator would not beannoyed at which switch to operate. In addition, in this state, thebeauty of the image reading apparatus can be increased.

A light source 106 g, which is constituted by a semiconductor lightsource, is mounted onto the circuit substrate 15 at two locationsthereof. For the semiconductor light source, a light-emitting diode(LED) or an organic light emitting diode (OLED) can be used.

In the present exemplary embodiment, the light is emitted from the lightsource 106 g in a direction horizontal to the surface of the operationpanel and in a direction of incidence of light to the light guideelement 103 g via the side of the light guide element 103 g.

When the light source 106 g is turned on, a diffused light flux, whichgoes around a direction of an arrow C, is incident to the light guideelement 103 g. The diffused light flux that has been incident to thelight guide element 103 g is repeatedly reflected within the light guideelement 103 g to be further transmitted.

On the bottom surface of the light guide element 103 g, a diffusionsurface 120 is formed by applying white coating (white paint) thereon.After being incident on the diffusion surface 120, the light isdiffusion-reflected and a part thereof is diffused upwards (in adirection indicated by an arrow “D”.

The light is shielded by the light-shielding layer 101 k but isexternally emitted from the transparent graphic portion 101 m.Accordingly, the symbols “+” and “−” become visually recognizable by theoperator. As described above, the backlight is constituted by the lightsource and the light guide element.

At a location on the circuit substrate 15 immediately below a touchingposition, i.e., at a location corresponding to the diffusion surface 120between two light sources 106 g, two electrodes 105 g are implemented toindependently detect the status of touching on the “+” and “−” keys. Inaddition, a signal processing circuit (including a processor), which iselectrically connected to each electrode, is installed on the circuitsubstrate 15.

The signal processing circuit converts the variation of the capacitance,which is detected at the electrode, into digital data. Furthermore, thesignal processing circuit executes signal processing to determine thestatus of switching (“on” and “off” states). When the operator touchesthe panel cover 11, the region of the panel cover 11 touched by theoperator by the fingertip and the electrode 105 g function as a kind ofa capacitor together. Accordingly, when the operator touches the surfaceof the panel cover 11 with his fingertip, the capacitance varies.

The signal processing circuit determines whether the panel cover 11 hasbeen touched by the operator according to a result of detection of thevariation of the capacitance by using the electrode 105 g.

If an input via the touch switch has been previously enabled, the signalprocessing circuit determines that a switch input has been executed(that the switch has been set “on”) if the capacitance detected by theelectrode has exceeded a predetermined threshold value. On the otherhand, if an input via the touch switch has been previously disabled, thesignal processing circuit discards the capacitance detected by using theelectrode or raises the above-described predetermined threshold value.

FIG. 4B is a B-B cross section of the capacitance touch switch atlocations of the arrow key 101 f, the jog wheel 101 d, and the OK key101 e illustrated in FIG. 2B. On the front surface of the panel cover11, a recessed dent is formed at a location thereof corresponding to theOK key 101 e.

Similarly, for the jog wheel 101 d, which has a ring-like shape, aring-like recessed dent (groove) is formed. No dents or grooves areformed at locations corresponding to the other keys.

By providing a dent to a highly frequently used key, the operator isenabled to always execute correct operations according to a sense oftouch and sight provided to the operator.

In particular, with respect to the jog wheel 101 d, because thering-shaped dent physically guides the motion of the operator's finger,the operator is enabled to smoothly slide his finger on the touchingsurface along correct locations. Accordingly, the operability of theapparatus can become high.

A light guide element 103 e is provided below the OK key 101 e. Fourlight guide elements 103 f are provided below the four arrow keys 101 f,respectively. Below the jog wheel 101 d, a ring-like shaped light guideelement 103 d is provided. Below the respective light guide elements 103e, 103 f, and 103 d, electrodes 105 e, 105 f, and 105 d are provided onthe circuit substrate 15.

A through hole 105 t is formed on the circuit substrate 15 at thelocation of each electrode. Air is released from the through hole 105 twhen attaching the light guide element group 13 and the circuitsubstrate 15 together by using the elastic sheet 14 on a large area.Accordingly, an air gap cannot easily arise between the elastic sheet 14and the surface of the electrode.

As described above, the present exemplary embodiment employs the gelsheet having high close-attachment properties as the elastic sheet 14.In addition, the present exemplary embodiment provides the through-hole105 t to the circuit substrate 15. Due to a synergetic effect of theseeffects, no air gap can easily arise during assembly of the operationpanel.

In the present exemplary embodiment, for the OK key 101 e and the jogwheel 101 d, the distance between the surface (touching surface) of thepanel cover 11 and the corresponding electrode is shorter than thedistance between the touching surface of the panel cover 11 and thearrow key 101 f by the dimension corresponding to the depth of therecessed dent. The variation of capacitance when touched by the operatormay become greater as the above-described distance becomes shorter.Accordingly, the greater the distance is, the detection sensitivity maybecome higher.

If the operator has touched the touching surface at the boundary betweenadjacent keys, it is likely that the OK key 101 e or the jog wheel 101d, whose detection sensitivity is high, may sense the touching operationby the operator. For the frequency of use as a switch, the OK key 101 eand the jog wheel 101 d have the greater frequency of use than that ofthe arrow key 101 f. Accordingly, the design in which the key having ahigher frequency of use preferentially detects the operator's operationis highly rational and useful.

More specifically, the plurality of touch switches includes mutuallyadjacent switches (a first switch (the OK key 101 e or the jog wheel 101d) and a second switch (the arrow key 101 f)) having different detectionsensitivity levels. The detection sensitivity of the first switch, whichis more frequently used of the two, is higher than that of the secondswitch.

For the OK key 101 e and the jog wheel 101 d, the distance to thecorresponding electrodes varies according to the location on the dent onthe panel cover 11. Due to the variation in the distance to thecorresponding electrode, the detection sensitivity of the capacitanceswitch can be different.

More specifically, for each of the OK key 101 e and the jog wheel 101 d,the dent implements two functions at the same time, i.e., a function forguiding the operator's finger and a function for adjusting the detectionsensitivity. Accordingly, the present exemplary embodiment implements ahigh operability and reliability with a simple configuration.

Particularly for the jog wheel 101 d, the location of the operator'sfinger may easily deviate from the intended position because theoperator moves his finger along the ring-like shape. However, becausethe ring-shaped dent physically guides the motion of the operator'sfinger, it is made as unlikely as possible that the operator's fingergoes off the intended position on the ring-shaped dent to touch thearrow key 101 f.

Even if the operator's finger has gone off the intended position, thejog wheel 101 d preferentially senses the touching operation due to thedifference in the detection sensitivity. With the combination of thephysical guidance of the operator's finger and the preferential orderaccording to the difference in the detection sensitivity, the presentexemplary embodiment can implement a very high operability andreliability.

Now, an exemplary state of display of the key in each of the pluralityof modes will be described in detail below with reference to FIGS. 5Athrough 5C.

FIG. 5A illustrates an exemplary state of display on the display unit 4and the panel cover 11 immediately after the apparatus has been bootedup by the operator operating the power button 111. On the display unit4, three functional icons, including a “scan” icon, a “copy” icon, and a“setting” icon, which can be selected at this timing, are displayed.

The “scan” icon corresponds to a scan mode. The “copy” icon correspondsto a copy mode. On the panel cover 11, three types of keys including thehome key 101 b, the left-right arrow keys 101 f, and the OK key 101 eonly are displayed.

If the operator touches either one key portion of the left-right arrowkey 101 f, a cursor 4 d displayed on the display unit 4 moves to theleft or right to switch the function to select. More specifically, ifthe operator desires to select the copy mode, the operator moves thecursor 4 d to the location below the copy icon and touches the OK key101 e. In this case, the operation mode shifts to the copy mode and thedisplay shifts to the display illustrated in FIG. 5B.

On the display unit 4, various setting menus for the copy mode aredisplayed. On the panel cover 11, the keys used in the copy mode onlyare displayed. The operator touches either one key portion of theup-down arrow key 101 f to set a paper type 4 e. Then, the operatortouches either one key portion of the left-right arrow key 101 f to seta copy density 4 f. Furthermore, the operator touches either one of the“+” key and the “−” key 101 g to set a number of copies 4 g. To select avalue of each of functions “preview” 4 h, “various copy modes” 4 i, and“detailed settings” 4 j, the operator touches either of the treefunctions keys 101 a, which are provided below each function. If theoperator touches the home key 101 b or the return key 101 c, the copymode ends and the display returns to the default display screenillustrated in FIG. 5A.

As illustrated in FIG. 5B, the backlight for the keys not used in thecopy mode is turned off to make them visually unrecognizable. If theoperator touches the visually unrecognizable keys, no input can beexecuted (any input is invalid) via the unrecognizable key.

Similarly, if the scan mode has been selected, the backlight for thekeys not used in the scan mode is turned off to make them visuallyunrecognizable. No input can be validly executed by operating thevisually unrecognizable keys.

In the copy mode or the scan mode, the operator sets the document on thereading surface 2. Accordingly, the operator opens and closes thepressing plate 6 by holding the same at the edges thereof. The presentexemplary embodiment can reduce the threat of causing a malfunction ofthe apparatus due to erroneous touching on the panel cover 11 with theoperator's finger to a minimum.

After the setting is completed, the operator touches either of themonochromatic copy key 101 h or the color copy key 101 i. Then, eitherof a monochromatic copy operation (in the scan mode, a monochromaticimage scan operation) and a color copy operation (in the scan mode, acolor image scan operation) is started. Then, the document set on thereading surface 2 is scanned by using the scanner of the reading unit.In the copy mode, the recording unit then prints the read document imagebased on the image data acquired by the reading operation.

In this case, the state of display on the display unit 4 and the panelcover 11 shifts to the display illustrated in FIG. 5C. Only the stop key101 j and the power button 111, which can be operated to instruct thediscontinuation of the current copy or the scan operation, can beoperated during the reading operation.

In this state, a message “copy in progress . . . ” (in the scan mode,“scan in progress . . . ”) is displayed. On the panel cover 11, the keysand buttons become visually unrecognizable except the stop key 101 j andthe power button 111. If the operator touches the unrecognizable key,the key does not sense the touching.

If a thick book document is set on the reading surface 2, the operatormay press the pressing plate 6 on its portion above the operation panelthereof to closely set the surface of the document onto the readingsurface 2. If the operator's hand or finger may have touched the switchon the panel cover 11, the switch does not sense the touching if theoperator has touched the stop key 101 j or the power button 111.Accordingly, an unintended input can be appropriately prevented.

In addition, most backlights have been turned off when the operatorpresses the document on the pressing plate 6. At this timing, theswitches are not visually recognizable to the user. Accordingly, theuser may not feel hesitated to press the document on the pressing plate6 on a portion above the operation panel.

Under control of the control unit 5, if the apparatus is left untouchedor unoperated in the state illustrated in FIG. 5A or 5B for apredetermined time, the apparatus automatically shifts to its sleep modefor saving power. In the sleep mode, the backlights for the operationkeys on the display unit 4 and the panel cover 11 are turned off toshift to the state illustrated in FIG. 2A.

In the sleep mode, the backlights are turned off. However, all theoperation keys can be operated to validly execute an input. Accordingly,if the operator touches the portion corresponding to an arbitraryoperation key, the touching operation is sensed and detected. Therefore,in this case, the operation mode shifts from the sleep mode to thenormal mode.

As described above, the apparatus of the present exemplary embodimentincludes the sleep mode in which the power consumption is smaller thanthat in the normal mode. In the normal mode, the backlight correspondingto the touch switch via which an input can be validly executed is turnedon while the backlight corresponding to the touch switch via which aninput cannot be validly executed is turned off. In the sleep mode, allthe plurality of backlights is turned off and the touch switch can beoperated to validly execute an input.

As described above, the apparatus according to the present exemplaryembodiment includes the operation panel having the capacitance touchswitch, which is provided on the upper surface of the pressing plate.Compared with a general mechanical switch, the switching surface of thecapacitance touch switch can be more firmly constructed.

Of the capacitance touch switch and a pressure-sensitive touch switch,the surface of the capacitance touch switch can be more firmlyconstructed. Accordingly, if the operator has pressed the switchingsurface of the switch in pressing the document by placing his hand onthe pressing plate, the apparatus according to the present exemplaryembodiment, which employs the capacitance touch switch as describedabove, can bear a very high pressure force.

It is particularly useful to employ the capacitance touch switch becauseit is necessary for the operator to press a book document by thepressing plate with a very high pressing force. Because the uppersurface of the pressing plate is an exposed surface, the operator mayspill some liquid of a beverage thereon or may bump a foreign materialthereon.

The capacitance switch which the exemplary embodiment of the presentinvention employs has a high resistance to a case where if any beverageis spilled or if a local impactive force is applied to the touch switch.

With the above-described configuration, the apparatus according to theexemplary embodiment of the present invention includes the backlights,each of which is provided for each of the plurality of touch switchesand which can be turned on and off independently from one another.Accordingly, the apparatus toggles each backlight for each of thecorresponding touch switches on and off according to the operation mode.

If the backlight corresponding to a key via which an input can bevalidly executed only is lit, the operator who is not accustomed tooperate the apparatus may not be annoyed for deciding which touch switchto operate.

In addition, when the operator presses a document by the pressing plate,if the backlight for the touch switch corresponding to an unused key hasbeen turned off, the operator can positively execute an operation viathe operation panel because the switch is appropriately visuallyunrecognizable in this case.

In addition, in the sleep mode, all the backlights of the touch switchcorresponding to all the keys are turned off but an input can be validlyexecuted thereby. More specifically, in the sleep mode, the operator canreturn the apparatus to the normal mode by merely pressing the operationpanel at an arbitrary location thereof.

Furthermore, the operator's finger touching the panel cover is guided bythe dent provided on the surface of the panel cover, which dent beingprovided at the location of the first switch. Accordingly, thedifference between the detection sensitivity of the first switch andthat of the second switch is secured. With this configuration, theexemplary embodiment of the present invention can implement a very highoperability and reliability with a simple configuration. It isparticularly very useful to provide the ring-shaped dent to the jogwheel (ring switch).

The shape of the jog wheel is not limited to a circular (ring) shape.More specifically, the jog wheel can take a polygonal ring-like shape.Furthermore, the ring-like shape of the jog wheel is not limited to acompletely continued closed shape. In other words, the ring-like shapecan include one or more breaks.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all modifications, equivalent structures, and functions.

This application claims priority from Japanese Patent Application No.2010-082796 filed Mar. 31, 2010, which is hereby incorporated byreference herein in its entirety.

1. An apparatus comprising: a reading unit configured to read an imageof a document set on a reading surface; a pressing plate capable ofopening relative to the reading surface; and an operation panel providedon an upper surface of the pressing plate, wherein the operation panelincludes: a cover; and a plurality of touch switches provided atdifferent locations of the cover, each touch switch including anelectrode configured to detect a capacitance, and wherein the pluralityof touch switches includes: a first switch and a second switch providedadjacent to each other, wherein a dent is formed on a surface of thecover at a location of the first switch, and wherein a distance betweenthe electrode and the surface of the cover at the location of the firstswitch is smaller than a distance between the electrode and the surfaceof the cover at the location of the second switch.
 2. The apparatusaccording to claim 1, wherein no dent is formed on the surface of thecover at the location of the second switch.
 3. The apparatus accordingto claim 1, wherein a backlight is provided for each of the plurality oftouch switches, and wherein control is executed for turning on thebacklight corresponding to the touch switch via which an input can bevalidly input and for turning off the backlight corresponding to thetouch switch via which an input cannot be validly input.
 4. Theapparatus according to claim 1, wherein the first switch includes aplurality of switches arranged in a ring-like shape, and wherein thesecond switch is adjacent to the first switch inside the ring-like shapeof the first switch.
 5. An operation device comprising: a cover; and aplurality of touch switches provided at different locations of thecover, each touch switch including an electrode configured to detect acapacitance, wherein the plurality of touch switches includes: a firstswitch and a second switch provided adjacent to each other, wherein adent is formed on a surface of the cover at a location of the firstswitch, and wherein a distance between the electrode and the surface ofthe cover at the location of the first switch is smaller than a distancebetween the electrode and the surface of the cover at the location ofthe second switch.